Many types of chairs, particularly office chairs, include a chair base that has a stand or castor base attached to a column. The column is usually attached to a seat frame, a tilt mechanism, or other chair component. The column is also typically configured for movement between different vertical positions.
Gas springs are often included in such columns. For instance, U.S. Pat. Nos. 5,765,804 and 5,433,409 disclose examples of different gas springs that may be utilized in chairs. The gas springs typically include a valve or other actuator at a top portion of the column. A portion of the gas cylinder is typically configured to extend into or out of another portion of the gas cylinder or a support attached to a portion of the chair base to effect height adjustment for the chair.
A number of different actuation mechanisms have been developed to actuate the height adjustment of gas springs or other columns of chair bases. For example, U.S. Pat. Nos. 5,577,804, 4,595,237, 4,408,800, and 4,072,288 disclose different types of height adjustment mechanisms that include such actuation devices.
Most, if not all, gas cylinders require a customized actuation mechanism to actuate height adjustment of a chair. Often, customization is required due to manufacturing tolerances between a chair component fabricator and a gas cylinder or other column supplier. Customization may also be required due to particular design considerations that must be made for other chair components.
The customization of gas cylinders and gas cylinder height adjustment actuation mechanisms significantly increases the costs of manufacturing a chair. A height adjustment mechanism is needed that does not require use of a particular, customized gas cylinder. Preferably, the height adjustment mechanism is designed for use with multiple different types of gas cylinders to permit a design manufacturer to solicit and receive purchase orders from multiple different suppliers of gas cylinders throughout the manufacturing life of a particular chair model.